This application claims the priority of German application 196 51 419.3 filed in Germany on Dec. 11, 1996, the disclosure of which is expressly incorporated by reference herein.
The present invention relates to an open-end spinning rotor comprising a sliding surface and a fiber collecting groove whose surface has fine roughenings.
An open-end spinning rotor described in German published patent application 195 09 742 A1 comprises a fiber collecting groove, which has fine roughenings in the micrometer range. In order to produce the roughenings, lasers are preferably used. A roughened surface is hereby produced which has the character of a wrinkled surface. The collecting groove obtains a favorable grip, which results in an improvement in the yarn. In order to increase the wear resistance, the surface of the fiber collecting groove is additionally boronized.
An open-end spinning rotor described in German published patent application 27 57 656 A1 has a sliding surface comprises wavelike profilings. The wave crests formed therefrom are equidistant to one another and have the same wave height. The fiber collecting groove is also preferably wave-shaped. The effective length of the fiber collecting groove is hereby increased, so that in particular long fibers can be deposited without any difficulties. The applicable area of the open-end spinning rotor is thus increased in relation to the staple length. The increase in the effective length is preferably 20%.
It is known from the U.S. Pat. No. 4,502,273 that in order to improve the wear resistance of the fiber collecting groove, an open-end spinning rotor made of steel is hardened by means of lasers. As the hardening can be localized very precisely, material distortion, which can otherwise occur during heat treatment, is avoided.
It is an object of the present invention to design the fiber collecting groove of an open-end spinning rotor in such a way that yarn quality is further improved.
This object has been achieved in accordance with the present invention in that the fiber collecting groove comprises profilings whose peak-to-valley height is at least five times the peak-to-valley height of the roughenings.
It has been shown that just that combination of relatively coarse profilings and fine roughenings result in an improvement in yarn quality. The improvement in yarn quality is marked by a higher yarn strength and a better evenness of the yarn. The fine roughenings ensure that the fibers arriving in the fiber collecting groove take up the rotational speed thereof practically without slip, while the coarser profilings result in an extension of the so-called fiber-integration zone, that is, an extension of the zone in which the single yarn twist is continued in the fiber collecting groove.
In accordance with the concept of the present invention, the peak-to-valley height of the roughenings is in the micrometer range, e.g. about 5 to 8 .mu.. Accordingly, the peak-to-valley height of the profilings is at least 25 .mu..
The profilings can be arranged in circumferential direction of the open-end spinning rotor at large distances to one another or directly adjacent to one another.
It is important that the profilings are arranged equidistant to one another, so that periodical discontinuities do not occur in the fiber collecting groove, which subsequently result in an undesirable moire effect in the fabric. It is furthermore favorable when the profilings are otherwise uniformly arranged or formed, for example, when they have at least approximately similarly dimensions. This results in a further improvement in yarn quality.
A smaller or larger amount of roughenings in the fiber collecting groove can be provided, according to the spinning conditions to which the open-end spinning rotor is adapted. The roughenings should be distributed over the entire circumference of the fiber collecting groove. In an advantageous way, such roughenings are contained on the surfaces of profilings, which roughenings partly or entirely cover the corresponding profilings.
In an advantageous embodiment of the present invention, the profilings form elevations and/or recesses, which extend transversely to the circumferential direction of the open-end spinning rotor. Transversely extending profilings of this type result in a further improvement in yarn quality, possibly because the extension of the single yarn twist into the fiber collecting groove is less hindered.
In an advantageous embodiment of the present invention, the profilings are arranged in a wave-like formation and form wave crests and wave troughs extending transversely to the circumferential direction of the open-end spinning rotor. Particularly good spinning results are achieved using a surface of this kind.
In a further advantageous embodiment of the present invention, the profilings are arranged in a honeycomb shape.
In an advantageous embodiment of the present invention, the fiber collecting groove is made of ceramic material. The surface form of the fiber collecting groove according to the present invention achieves good spinning results with this very wear-resistant material.
In a further advantageous embodiment of the present invention, the fiber collecting groove is made of boronized steel. It has been shown that the surface form according to the present invention achieves particularly good spinning results when the fiber collecting groove is boronized. At the same time, a long life for the fiber collecting groove is obtained. Even after many operational hours, the spinning results deteriorate only slightly due to the hardness of the surface. Thus the double requirement of good spinning properties and long life are both fulfilled. These requirements were seen up to now as mutually exclusive. It is practical for the purposes of the present invention to apply the surface form to the already boronized collecting groove. This results in better yarn quality in comparison to collecting grooves which are boronized after the surface of the present invention has been applied.
The profilings and roughenings can be produced in various ways, for example by mechanical means. It is also possible to use material for the fiber collecting groove which already comprises the desired roughenings due to its inherent character.
In an advantageous embodiment of the present invention, the roughenings and profilings are produced by laser. It has been shown that the specific surface form obtained by means of lasers gives particularly good spinning results. A further advantage is that the laser settings can be adjusted very easily. Thus very varying surface forms of the fiber collecting groove can be obtained, according to the spinning specifications required. Lasers can be applied with good results to all materials used for open-end spinning rotors, in particular to hard materials, such as ceramic or iron boride.
In an advantageous way, the production of profilings and roughenings takes place in the same procedural step.
In an advantageous way, unhardened steel is used for the fiber collecting groove, which is hardened by means of lasers. This can take place, in an advantageous way, in the same procedural step in which the profilings and roughenings are produced by lasers. A good protection against wear can thus be obtained in a cost-effective way. In an advantageous embodiment, the fiber sliding surface also comprises profilings which are directed towards the fiber collecting groove. These profilings are also produced in an advantageous way by means of lasers.